Prior underfed balers have, for the most part, utilized a pair of separate feeder devices for moving crop materials from the discharge point of the crop pickup to the baling chamber itself. For example, in White U.S. Pat. No. 4,157,643 a first rotary device at the mouth end of the loading duct sweeps material into the duct and fills the latter until such time as a second device in the form of a stuffing fork commences its cycle to stuff the charge up into the bottom of the baling chamber.
Similarly, in Swenson et al U.S. Pat. No. 4,275,550, a first rotary device at the lower mouth end of the duct sweeps material into the open mouth and up into the duct where it is thereupon stuffed up into the bale chamber by a second device in the form of a loading fork.
The baler in Murray U.S. Pat. No. 3,552,109 uses a single stuffing fork to take materials from the pickup and lift the same up through the duct into the bottom of the chamber, but in this machine the stuffer is incapable of loading a charge which extends across the full vertical height of the baling chamber. Instead, each cycle of the stuffer simply adds another small wad of material to those already collected in the bale chamber, each wad being considerably smaller than that which is required to fill the entire area of the chamber vertically and horizontally across the front face of the bale forming therein. The crop package which results from this machine is of relatively low density made up of many discrete, independent wads or bundles of crop materials throughout all areas of the package instead of a series of rectangular, dense "flakes" compacted together along the length of the bale and each of which corresponds in height and width to the internal configurations of the bale chamber.